Apparatus for susceptor temperature verification and methods of use

ABSTRACT

Apparatus and methods for processing a semiconductor wafer in which a sensor (e.g., a contact thermocouple) is positioned in the gas distribution assembly measures temperature and/or a film parameter before, during and/or after deposition are described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/981,731, filed Apr. 18, 2014, the entire disclosure of which ishereby incorporated by reference herein.

FIELD

Embodiments of the disclosure generally relate to apparatus and methodsof processing a substrate. In particular, embodiments of the disclosureare directed to apparatus and methods for measuring temperature andother parameters of substrates before, during and/or after processing.

BACKGROUND

The process of forming semiconductor devices is commonly conducted insubstrate processing platforms containing multiple processing chambers.In some instances, the purpose of a multi-chamber processing platform,or cluster tool, is to perform two or more processes on a substratesequentially in a controlled environment. In other instances, a multiplechamber processing platform may perform a single processing step onsubstrates; the additional chambers used to maximize the rate at whichsubstrates are processed by the platform. In the latter case, theprocess performed on substrates is typically a batch process, wherein arelatively large number of substrates, e.g. 25 or 50, are processed in agiven chamber simultaneously. Batch processing is especially beneficialfor processes that are too time-consuming to be performed on individualsubstrates in an economically viable manner, such as for ALD processesand some chemical vapor deposition (CVD) processes.

The effectiveness of a substrate processing platform, or system, isoften quantified by cost of ownership (COO). The COO, while influencedby many factors, is largely affected by the system footprint, i.e., thetotal floor space used to operate the system in a fabrication plant, andsystem throughput, i.e., the number of substrates processed per hour.Footprint typically includes access areas adjacent the system that areused for maintenance. Hence, although a substrate processing platformmay be relatively small, if the system requires access from all sidesfor operation and maintenance, the system's effective footprint maystill be prohibitively large.

The semiconductor industry's tolerance for process variability continuesto decrease as the size of semiconductor devices shrink. To meet thetighter process requirements, the industry has developed a host of newprocesses which often take a longer time to complete. For example, forforming a copper diffusion barrier layer conformally onto the surface ofa high aspect ratio, 65 nm or smaller interconnect feature, to use anALD process may be used. ALD is a variant of CVD that demonstratessuperior step coverage compared to CVD. ALD is based upon atomic layerepitaxy (ALE) that was originally employed to fabricateelectroluminescent displays. ALD employs chemisorption to deposit asaturated monolayer of reactive precursor molecules on a substratesurface. This is achieved by cyclically alternating the pulsing ofappropriate reactive precursors into a deposition chamber. Eachinjection of a reactive precursor, or reactive gas, is typicallyseparated by an inert gas purge to provide a new atomic layer toprevious deposited layers to form an uniform material layer on thesurface of a substrate. Cycles of reactive precursor and inert purgegases are repeated to form the material layer to a predeterminedthickness. The biggest drawback with ALD techniques is that thedeposition rate is much lower than typical CVD techniques by at least anorder of magnitude. For example, some ALD processes can require achamber processing time from about 10 to about 200 minutes to deposit ahigh quality layer on the surface of the substrate. In choosing such ALDand epitaxy processes for better device performance, the cost tofabricate devices in a conventional single substrate processing chamberwould increase due to very low substrate processing throughput. Hence,when implementing such processes, a continuous substrate processingapproach is needed to be economically feasible.

Evaluating a deposition process dynamically provides a rapid andaccurate means to determining the quality of deposited films and processcompletion. However, optical measurements of a wafer (e.g., temperature,film characteristics) in a carousel-type processing chamber cannot beperformed while processing. Positioning optical devices in theprocessing chamber during deposition (e.g., pyrometers) can beproblematic because the optical instruments become fouled by thedeposition reaction, rendering them unsuitable for use.

Measuring the temperature of a large platen susceptor in a batchprocessing system can also be difficult due to the distance between thegas distribution assembly and the susceptor assembly. Therefore, thereis a need for apparatus and methods that can accurately measure thesusceptor temperature without interfering with the processing chamberfunctions.

SUMMARY

Embodiments of the disclosure are directed to processing chamberscomprising a susceptor assembly and a gas distribution assembly. Thesusceptor assembly includes a top surface to support and rotate aplurality of substrates around a central axis. The top surface has aninner peripheral edge and an outer peripheral edge. The gas distributionassembly is above the susceptor assembly and comprises a plurality ofelongate gas ports to direct flows of gases toward the susceptorassembly and at least one sensor positioned to contact the susceptorassembly during measurement.

Additional embodiments of the disclosure are directed to processingchambers comprising a susceptor assembly, a gas distribution assemblyand a contact thermocouple. The susceptor assembly includes a topsurface to support and rotate a plurality of substrates around a centralaxis. The top surface has an inner peripheral edge and an outerperipheral edge. The gas distribution assembly is above the susceptorassembly and comprises a plurality of elongate gas ports to direct flowsof gases toward the susceptor assembly. The contact thermocouple ispositioned within an inert gas region of the gas distribution assemblyto contact the susceptor assembly during measurement.

Further embodiments of the disclosure are directed to methods ofprocessing at least one substrate in a processing chamber. The at leastone substrate is positioned in a recess in a top surface of a susceptorassembly. The substrate has a top surface. The substrate and susceptorassembly are passed under a gas distribution assembly comprising aplurality of substantially parallel gas channels directing flows ofgases toward the top surface of the substrate to deposit a film on thetop surface of the substrate. A measurement is taken from a sensorpositioned at an inert region of the gas distribution assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the disclosureare attained and can be understood in detail, a more particulardescription of the disclosure, briefly summarized above, may be had byreference to the embodiments thereof which are illustrated in theappended drawings. It is to be noted, however, that the appendeddrawings illustrate only typical embodiments of this disclosure and aretherefore not to be considered limiting of its scope, for the disclosuremay admit to other equally effective embodiments.

FIG. 1 is a partial cross-sectional side view of a spatial atomic layerdeposition chamber in accordance with one or more embodiment of thedisclosure;

FIG. 2 shows a perspective view of a susceptor in accordance with one ormore embodiments of the disclosure;

FIG. 3 shows a schematic of a pie-shaped gas distribution assembly inaccordance with one or more embodiments of the disclosure;

FIG. 4 is a schematic plan view of a substrate processing systemconfigured with four gas distribution assemblies and four inductivelycoupled pie-shaped plasma sources with a loading station in accordancewith one or more embodiments of the disclosure;

FIG. 5 is a front view of a gas distribution plate with sensors inaccordance with one or more embodiment of the disclosure; and

FIG. 6 shows a movable contact thermocouple in accordance with one ormore embodiments of the disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments of the disclosure are directed to apparatus and methods fortaking optical measurements of a wafer before, during and/or afterprocessing. As used in this specification and the appended claims, theterm “substrate” and “wafer” are used interchangeably, referring to asurface, or portion of a surface, upon which a process acts. It willalso be understood by those skilled in the art that reference to asubstrate can also refer to a portion of the substrate, unless thecontext clearly indicates otherwise. For example, in spatially separatedALD, described with respect to FIG. 1, each precursor is delivered tothe substrate, but any individual precursor stream, at any given time,is only delivered to a portion of the substrate. Additionally, referenceto depositing on a substrate can mean both a bare substrate and asubstrate with one or more films or features deposited or formedthereon.

As used in this specification and the appended claims, the terms“reactive gas”, “precursor”, “reactant”, and the like, are usedinterchangeably to mean a gas that comprises a species which is reactivein an atomic layer deposition process. For example, a first “reactivegas” may simply adsorb onto the surface of a substrate and be availablefor further chemical reaction with a second reactive gas.

Embodiments of the disclosure provide apparatus and methods to takeoptical measurements during carousel processing. As used in thisspecification and the appended claims, the term “during carouselprocessing,” and the like, means that the subject action can be taken atany point in a process sequence, including, but not limited to, waferloading/unloading and deposition. Those skilled in the art willunderstand that some measurements can be taken while the susceptor isrotating while some measurements may be taken when the susceptor isstationary. The timing of the measurement can depend on, for example,the type of measurement and the type of measurement device.

The carousel spatial ALD showerhead of one or more embodiments hassegregated sections within the injector design which are substantiallyfree of reactive gas flows. Therefore, no film can be deposited on anoptical instrument positioned in the segregated sections locations. Dueto the segregated sections within the injector design, pyrometers,interferometers and related devices can be installed to gain activetemperature and film characterization data of the actual processenvironment. Data can be acquired before, during and/or afterprocessing. The placement of the optical instruments can read thesusceptor or wafer at the inner diameter, middle or outer diameterregions from the top side of the wafer.

FIG. 1 is a schematic cross-sectional view of a portion of a processingchamber 20 in accordance with one or more embodiments of the disclosure.The processing chamber 20 is generally a sealable enclosure, which isoperated under vacuum, or at least low pressure conditions. The chamber100 includes a gas distribution assembly 30 capable of distributing oneor more gases across the top surface 61 of a substrate 60. The gasdistribution assembly 30 can be any suitable assembly known to thoseskilled in the art, and specific gas distribution assemblies describedshould not be taken as limiting the scope of the disclosure. The outputface of the gas distribution assembly 30 faces the first surface 61 ofthe substrate 60.

Substrates for use with the embodiments of the disclosure can be anysuitable substrate. In some embodiments, the substrate is a rigid,discrete, generally planar substrate. As used in this specification andthe appended claims, the term “discrete” when referring to a substratemeans that the substrate has a fixed dimension. The substrate of one ormore embodiments is a semiconductor substrate, such as a 200 mm or 300mm diameter silicon substrate. In some embodiments, the substrate is oneor more of silicon, silicon germanium, gallium arsenide, galliumnitride, germanium, gallium phosphide, indium phosphide, sapphire andsilicon carbide.

The gas distribution assembly 30 comprises a plurality of gas ports totransmit one or more gas streams to the substrate 60 and a plurality ofvacuum ports disposed between each gas port to transmit the gas streamsout of the processing chamber 20. In the embodiment of FIG. 1, the gasdistribution assembly 30 comprises a first precursor injector 120, asecond precursor injector 130 and a purge gas injector 140. Theinjectors 120, 130, 140 may be controlled by a system computer (notshown), such as a mainframe, or by a chamber-specific controller, suchas a programmable logic controller. The precursor injector 120 injects acontinuous (or pulse) stream of a reactive precursor of compound A intothe processing chamber 20 through a plurality of gas ports 125. Theprecursor injector 130 injects a continuous (or pulse) stream of areactive precursor of compound B into the processing chamber 20 througha plurality of gas ports 135. The purge gas injector 140 injects acontinuous (or pulse) stream of a non-reactive or purge gas into theprocessing chamber 20 through a plurality of gas ports 145. The purgegas removes reactive material and reactive by-products from theprocessing chamber 20. The purge gas is typically an inert gas, such as,nitrogen, argon and helium. Gas ports 145 are disposed in between gasports 125 and gas ports 135 so as to separate the precursor of compoundA from the precursor of compound B, avoiding cross-contamination betweenthe precursors.

In another aspect, a remote plasma source (not shown) may be connectedto the precursor injector 120 and the precursor injector 130 prior toinjecting the precursors into the processing chamber 20. The plasma ofreactive species may be generated by applying an electric field to acompound within the remote plasma source. Any power source that iscapable of activating the intended compounds may be used. For example,power sources using DC, radio frequency (RF), and microwave (MW) baseddischarge techniques may be used. If an RF power source is used, thepower source can be either capacitively or inductively coupled. Theactivation may also be generated by a thermally based technique, a gasbreakdown technique, a high energy light source (e.g., UV energy), orexposure to an x-ray source. Exemplary remote plasma sources areavailable from vendors such as MKS Instruments, Inc. and Advanced EnergyIndustries, Inc.

The chamber 100 further includes a pumping system 150 connected to theprocessing chamber 20. The pumping system 150 is generally configured toevacuate the gas streams out of the processing chamber 20 through one ormore vacuum ports 155. The vacuum ports 155 are disposed between eachgas port so as to evacuate the gas streams out of the processing chamber20 after the gas streams react with the substrate surface and to furtherlimit cross-contamination between the precursors. The chamber 100includes a plurality of partitions 160 disposed on the processingchamber 20 between each port. A lower portion of each partition extendsclose to the first surface 61 of substrate 60, for example, about 0.5 mmor greater from the first surface 61. In this manner, the lower portionsof the partitions 160 are separated from the substrate surface by adistance sufficient to allow the gas streams to flow around the lowerportions toward the vacuum ports 155 after the gas streams react withthe substrate surface. Arrows 198 indicate the direction of the gasstreams. Since the partitions 160 operate as a physical barrier to thegas streams, they also limit cross-contamination between the precursors.The arrangement shown is merely illustrative and should not be taken aslimiting the scope of the disclosure. It will be understood by thoseskilled in the art that the gas distribution system shown is merely onepossible distribution system and the other types of showerheads and gasdistribution assemblies may be employed.

Atomic layer deposition systems of this sort (i.e., where multiple gasesare separately flowed toward the substrate at the same time) arereferred to as spatial ALD. In operation, a substrate 60 is delivered(e.g., by a robot) to the processing chamber 20 and can be placed on ashuttle 65 before or after entry into the processing chamber. Theshuttle 65 is moved along the track 70, or some other suitable movementmechanism, through the processing chamber 20, passing beneath (or above)the gas distribution assembly 30. In the embodiment shown in FIG. 1, theshuttle 65 is moved in a linear path through the chamber. FIG. 3, asexplained further below, shows an embodiment in which wafers are movedin a circular path through a carousel processing system.

Referring back to FIG. 1, as the substrate 60 moves through theprocessing chamber 20, the first surface 61 of substrate 60 isrepeatedly exposed to the reactive gas A coming from gas ports 125 andreactive gas B coming from gas ports 135, with the purge gas coming fromgas ports 145 in between. Injection of the purge gas is designed toremove unreacted material from the previous precursor prior to exposingthe substrate surface 110 to the next precursor. After each exposure tothe various gas streams (e.g., the reactive gases or the purge gas), thegas streams are evacuated through the vacuum ports 155 by the pumpingsystem 150. Since a vacuum port may be disposed on both sides of eachgas port, the gas streams are evacuated through the vacuum ports 155 onboth sides. Thus, the gas streams flow from the respective gas portsvertically downward toward the first surface 61 of the substrate 60,across the substrate surface 110 and around the lower portions of thepartitions 160, and finally upward toward the vacuum ports 155. In thismanner, each gas may be uniformly distributed across the substratesurface 110. Arrows 198 indicate the direction of the gas flow.Substrate 60 may also be rotated while being exposed to the various gasstreams. Rotation of the substrate may be useful in preventing orminimizing the formation of strips in the formed layers. Rotation of thesubstrate can be continuous or in discrete steps and can occur while thesubstrate is passing beneath the gas distribution assembly 30 or whenthe substrate is in a region before and/or after the gas distributionassembly 30.

Sufficient space is generally provided after the gas distributionassembly 30 to ensure complete exposure to the last gas port. Once thesubstrate 60 has passed beneath the gas distribution assembly 30, thefirst surface 61 has been exposed to every gas port in the processingchamber 20. The substrate can be transported back in the oppositedirection or forward. If the substrate 60 moves in the oppositedirection, the substrate surface may be exposed again to the reactivegas A, the purge gas, and reactive gas B, in reverse order from thefirst exposure.

The extent to which the substrate surface 110 is exposed to each gas maybe determined by, for example, the flow rates of each gas coming out ofthe gas port and the rate of movement of the substrate 60. In oneembodiment, the flow rates of each gas are controlled so as not toremove adsorbed precursors from the substrate surface 61. The widthbetween each partition, the number of gas ports disposed on theprocessing chamber 20, and the number of times the substrate is passedacross the gas distribution assembly may also determine the extent towhich the substrate surface 61 is exposed to the various gases.Consequently, the quantity and quality of a deposited film may beoptimized by varying the above-referenced factors.

Although description of the process has been made with the gasdistribution assembly 30 directing a flow of gas downward toward asubstrate positioned below the gas distribution assembly, those skilledin the art will understand that this orientation can be different. Insome embodiments, the gas distribution assembly 30 directs a flow of gasupward toward a substrate surface. As used in this specification and theappended claims, the term “passed across” means that the substrate hasbeen moved from one side of the gas distribution assembly to the otherside so that the entire surface of the substrate is exposed to each gasstream from the gas distribution plate. Absent additional description,the term “passed across” does not imply any particular orientation ofgas distribution assemblies, gas flows or substrate positions.

In some embodiments, the shuttle 65 is a susceptor 66 for carrying thesubstrate 60. Generally, the susceptor 66 is a carrier which helps toform a uniform temperature across the substrate. The susceptor 66 ismovable in both directions (left-to-right and right-to-left, relative tothe arrangement of FIG. 1) or in a circular direction (relative to FIG.3). The susceptor 66 has a top surface 67 for carrying the substrate 60.The susceptor 66 may be a heated susceptor so that the substrate 60 maybe heated for processing. As an example, the susceptor 66 may be heatedby radiant heat lamps 90, a heating plate, resistive coils, or otherheating devices, disposed underneath the susceptor 66.

In another embodiment, the top surface 67 of the susceptor 66 includes arecess 68 to accept the substrate 60, as shown in FIG. 2. The susceptor66 is generally thicker than the thickness of the substrate so thatthere is susceptor material beneath the substrate. In some embodiments,the recess 68 is sized such that when the substrate 60 is disposedinside the recess 68, the first surface 61 of substrate 60 is levelwith, or substantially coplanar with, the top surface 67 of thesusceptor 66. Stated differently, the recess 68 of some embodiments issized such that when a substrate 60 is disposed therein, the firstsurface 61 of the substrate 60 does not protrude above the top surface67 of the susceptor 66. As used in this specification and the appendedclaims, the term “substantially coplanar” means that the top surface ofthe wafer and the top surface of the susceptor assembly are coplanarwithin ±0.2 mm. In some embodiments, the top surfaces are coplanarwithin ±0.15 mm, ±0.10 mm or ±0.05 mm.

FIG. 1 shows a cross-sectional view of a processing chamber in which theindividual gas ports are shown. This embodiment can be either a linearprocessing system in which the width of the individual gas ports issubstantially the same across the entire width of the gas distributionplate, or a pie-shaped segment in which the individual gas ports changewidth to conform to the pie shape. FIG. 3 shows a portion of apie-shaped gas distribution assembly 30. A substrate would be passedacross this gas distribution assembly 30 in an arc shape path 32. Eachof the individual gas ports 125, 135, 145, 155 extend from an innerperipheral region to an outer peripheral region of the gas distributionassembly 30 and have a narrower width near the inner peripheral edge 33of the gas distribution assembly 30 a and a larger width near the outerperipheral edge 34 of the gas distribution assembly 30. The shape oraspect ratio of the individual ports can be proportional to, ordifferent from, the shape or aspect ratio of the gas distributionassembly 30 segment. In some embodiments, the individual ports areshaped so that each point of a wafer passing across the gas distributionassembly 30 following path 32 would have about the same residence timeunder each gas port. The path of the substrates can be perpendicular tothe gas ports. In some embodiments, each of the gas distributionassemblies comprises a plurality of elongate gas ports which extend in adirection substantially perpendicular to the path traversed by asubstrate. As used in this specification and the appended claims, theterm “substantially perpendicular” means that the general direction ofmovement is approximately perpendicular to the axis of the gas ports.For a pie-shaped gas port, the axis of the gas port can be considered tobe a line defined as the mid-point of the width of the port extendingalong the length of the port.

Processing chambers having multiple gas injectors can be used to processmultiple wafers simultaneously so that the wafers experience the sameprocess flow. For example, as shown in FIG. 4, the processing chamber100 has four gas distribution assemblies 30 and four substrates 60. Atthe outset of processing, the substrates 60 can be positioned betweenthe gas distribution assemblies 30. Rotating the susceptor 66 of thecarousel by 45° will result in each substrate 60 being moved to an gasdistribution assembly 30 for film deposition. An additional 45° rotationwould move the substrates 60 away from the gas distribution assemblies30. This is the position shown in FIG. 4. With spatial ALD injectors, afilm is deposited on the wafer during movement of the wafer relative tothe injector assembly. In some embodiments, the susceptor 66 is rotatedso that the substrates 60 do not stop beneath the gas distributionassemblies 30. The number of substrates 60 and gas distributionassemblies 30 can be the same or different. In some embodiments, thereare the same numbers of wafers being processed as there are gasdistribution assemblies. In one or more embodiments, the number ofwafers being processed are an integer multiple of the number of gasdistribution assemblies. For example, if there are four gas distributionassemblies, there are 4x wafers being processed, where x is an integervalue greater than or equal to one.

The processing chamber 100 shown in FIG. 4 is merely representative ofone possible configuration and should not be taken as limiting the scopeof the disclosure. Here, the processing chamber 100 includes a pluralityof gas distribution assemblies 30. In the embodiment shown, there arefour gas distribution assemblies 30 evenly spaced about the processingchamber 100. The processing chamber 100 shown is octagonal, however,those skilled in the art will understand that this is one possible shapeand should not be taken as limiting the scope of the disclosure. The gasdistribution assemblies 30 shown are trapezoidal, but those skilled inthe art will understand that the gas distribution assemblies can be anysuitable shape, for example, pie-shaped segments like that shown in FIG.3.

The processing chamber 100 includes a substrate support apparatus, shownas a round susceptor 66 or susceptor assembly. The substrate supportapparatus, or susceptor 66, is capable of moving a plurality ofsubstrates 60 beneath each of the gas distribution assemblies 30. A loadlock 82 might be connected to a side of the processing chamber 100 toallow the substrates 60 to be loaded/unloaded from the chamber 100.

In some embodiments, the processing chamber comprises a plurality of gascurtains (not shown) positioned between the gas distribution assemblies30 and the plasma stations 80. Each gas curtain can creates a barrier toprevent, or minimize, the movement of processing gases from the gasdistribution assemblies 30 from migrating from the gas distributionassembly regions and gases from the plasma sources 80 from migratingfrom the plasma regions. The gas curtain can include any suitablecombination of gas and vacuum streams which can isolate the individualprocessing sections from the adjacent sections. In some embodiments, thegas curtain is a purge (or inert) gas stream. In one or moreembodiments, the gas curtain is a vacuum stream that removes gases fromthe processing chamber. In some embodiments, the gas curtain is acombination of purge gas and vacuum streams so that there are, in order,a purge gas stream, a vacuum stream and a purge gas stream. In one ormore embodiments, the gas curtain is a combination of vacuum streams andpurge gas streams so that there are, in order, a vacuum stream, a purgegas stream and a vacuum stream.

In some embodiments, sensors are positioned within the purge gas portsof a gas distribution assembly in a spatial ALD processing chamber.While the sensors may be shown in the purge gas ports, those skilled inthe art will understand that the sensors can be placed at any suitablelocation. Positioning the sensors in the purge gas channel may helpminimize or eliminate sensor exposure to corrosive chemicals ordeposition gases which may decrease the accuracy and/or precision of thesensors.

In one or more embodiments, contact sensors which move betweennon-contact and contact positions are included. When not in use, thecontact sensors can be retracted to a non-contact position where up tothe entire sensor is enveloped in an inert gas shroud. When employed,the contact sensors are extended from the purge gas channel to a contactposition where they touch the susceptor assembly.

Large batch processing chambers can have any suitable number of sensorspositioned about the interior of the processing chamber. In someembodiments there are 1 or 2 sensors in each of the purge gas ports. Thesensors can be any type of suitable sensor including, but not limitedto, contact thermocouples and pyrometers. The type of sensors used canbe the same throughout the processing chamber, or can include differenttypes. For example, in one or more embodiments, each of the purge gasports has a contact thermocouple and a pyrometer.

During processing, monitoring the temperature of the susceptor assemblyand/or wafers or monitoring a specific property of the film beingdeposited may be useful. For example, measuring the emissivity of thefilm during formation. Embodiments of the disclosure have a sensor on orin the gas distribution assembly which can directly measure temperature,and a number of other, parameters during processing. Those skilled inthe art will understand that the term “during processing” can mean whilethe susceptor is moving, or during a pause in rotation.

Accordingly, one or more embodiments of the disclosure are directed to aprocessing chamber comprising a susceptor assembly 66 and a gasdistribution assembly 30. The susceptor assembly 66 includes a topsurface 67 to support and rotate a plurality of substrates 60 around 17a central axis 18. The top surface 67 of the susceptor assembly 66 hasan inner peripheral edge 92 and an outer peripheral edge 91. The gasdistribution assembly 30 is positioned above the susceptor assembly 66.As shown in FIG. 5, the gas distribution assembly 30 comprises aplurality of elongate gas ports 125, 135, 145 to direct flows of gasestoward the susceptor assembly 66 and elongate vacuum ports 155 to directflows of gases out of the processing chamber. In some embodiments, theelongate gas ports include a first reactive gas port (i.e., gas port125) that delivers a first reactive gas and a second reactive gas port(i.e., gas ports 135) that delivers a second reactive gas. The elongategas ports may also include at least one vacuum port. The gasdistribution assembly 30 also includes at least one sensor 95 directedtoward the susceptor assembly 66. In some embodiments, the at least onsensor 95 comprises a contact thermocouple and is positioned to touchthe surface of the susceptor assembly 66.

The sensors 95 shown in FIG. 5 are located between a vacuum port 155(also referred to as a pump port) and a purge port 145, which may bereferred to as an inert region or inert gas region. The inert region, orinert gas region, is an area in which the gases are substantially inertrelative to the sensors. In the inert region, in theory, only purgegases and/or vacuum streams might come into contact with the sensor 95.In some embodiments, the sensor 95 is located within a purge gas port145. In this position, in theory, only purge gases can flow past thesensor 95 and may keep a steady flow of inert gas (i.e., forming aninert gas envelope) around the sensor 95. The sensors 95 are positionedto measure points on the susceptor assembly near the inner peripheraledge and the outer peripheral edge of the susceptor assembly, as well asa middle region which could be a susceptor assembly or wafer, dependingon at what point measurement is taken during processing.

The sensor 95 can be positioned directly on the surface of the gasdistribution assembly 30 or in a recess or hole 96 in the gasdistribution plate. The hole 96 can be any suitable size depending onthe size of the sensor 95. In some embodiments, the hole 96 is up toabout 10 mm in diameter. In some embodiments, there is at least one hole95 in which at least one sensor 95 can be positioned.

In some embodiments, the sensor 95 comprises one or more of a contactthermocouple, contact thermistor or contact resistance temperaturedetector. As used in this specification and the appended claims, theterm “contact thermocouple” is used to describe any type of temperaturemeasurement sensor that contacts the surface being measured.

FIG. 6 shows another embodiment of the disclosure with a movable contactsensor 95. Here, three sensors 95 are connected to a support bar 97which is moved by a handle 99 connected to a lever 92. The position ofthe base 98 is fixed so that the support bar 97 can slide, or move,between non-contact and contact positions. The embodiment shown in FIG.6 includes a manual handle 99 but those skilled in the art willunderstand that a motorized actuator can be employed which can becontrolled by any suitable controller, such as the controller thathandles the rest of the processing chamber systems.

In some embodiments, there are at least two contact thermocouples tomeasure temperature. At least one of the contact thermocouples ispositioned to measure temperature near the inner peripheral edge of thesusceptor assembly and at least one of the contact thermocouples ispositioned to measure temperature near the outer peripheral edge of thesusceptor assembly.

Although the disclosure herein has been described with reference toparticular embodiments, the embodiments are merely illustrative of theprinciples and applications of the present disclosure. Those skilled inthe art will understand that various modifications and variations can bemade to the method and apparatus of the present disclosure withoutdeparting from the spirit and scope of the disclosure. Thus, the presentdisclosure includes modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A processing chamber comprising: a susceptorassembly including a top surface to support and rotate a plurality ofsubstrates around a central axis, the top surface having an innerperipheral edge and an outer peripheral edge, the top surface includinga plurality of recesses formed therein, the recesses sized to support anedge of a wafer so that a wafer supported in the recess has a topsurface substantially coplanar with the top surface of the susceptorassembly; and a gas distribution assembly above the susceptor assembly,the gas distribution assembly comprising a plurality of elongate gasports to direct flows of gases toward the susceptor assembly, theelongate gas ports including a first reactive gas port, a secondreactive gas port, a purge gas port and at least one vacuum port, thegas distribution assembly including at least one sensor positioned tocontact the susceptor assembly during measurement, the sensor positionedin an inert gas region of the gas distribution assembly between thefirst reactive gas port and the second reactive gas port so thatsubstantially only purge gases come into contact with the sensor while afirst reactive gas is flowing through the first reactive gas port and asecond reactive gas is flowing through the second reactive gas port, theat least one sensor connected to a support bar connected to a base, thebase fixed so that the support bar can move between non-contact andcontact positions to move the at least one sensor connected to thesupport bar between a non-contact and contact position.
 2. Theprocessing chamber of claim 1, wherein the at least one sensor ispositioned within a purge gas port.
 3. The processing chamber of claim1, wherein the at least one sensor is positioned within a hole.
 4. Theprocessing chamber of claim 1, wherein the at least one sensor comprisesa contact thermocouple.
 5. The processing chamber of claim 4, whereinthe contact thermocouple moves from a non-contact position to a contactposition for measurement.
 6. The processing chamber of claim 5, whereinthere are at least two sensors to measure temperature, at least onesensor positioned to measure temperature near the inner peripheral edgeof the susceptor assembly and at least one sensor positioned to measuretemperature near the outer peripheral edge of the susceptor assembly. 7.The processing chamber of claim 1, further comprising a controller incommunication with the at least one sensor to analyze data from thesensor.
 8. A processing chamber comprising: a susceptor assemblyincluding a top surface to support and rotate a plurality of substratesaround a central axis, the top surface having an inner peripheral edgeand an outer peripheral edge and a plurality of recesses sized so that awafer supported in the recess has a top surface substantially coplanarwith the top surface of the susceptor assembly; a gas distributionassembly above the susceptor assembly, the gas distribution assemblycomprising a plurality of elongate gas ports to direct flows of gasestoward the susceptor assembly, the elongate gas ports including a firstreactive gas port and a second reactive gas port, the first reactive gasport and second reactive gas port separated by an inert gas port withvacuum ports on either side of the inert gas port, the vacuum ports andinert gas port forming an inert gas region; and at least two contactthermocouples positioned within the inert gas region of the gasdistribution assembly to contact the susceptor assembly duringmeasurement, at least one contact thermocouple positioned to measuretemperature near the inner peripheral edge of the susceptor assembly andat least one contact thermocouple positioned to measure temperature nearthe outer peripheral edge of the susceptor assembly, wherein at leasttwo thermocouples are connected to a support bar connected to a base,the base fixed so that the support bar can move between non-contact andcontact positions to move the thermocouples connected to the support barat the same time.
 9. The processing chamber of claim 8, furthercomprising an actuator connected support bar to move the thermocouplesconnected to the support bar at the same time.
 10. The processingchamber of claim 8, further comprising a controller in communicationwith the at least one sensor to analyze data from the sensor.